Refrigerant Side Economizer

ABSTRACT

This invention provides a Refrigerant Side Economizer cycle and a fuel-heat based heating cycle for air conditioners, heat pumps, and chillers. The built-in refrigerant side economizer cycle can be substituted for an air-side economizer cycle or a water-side economizer cycle. It can provide an economizer cycle for split system air conditioners, chillers, coolers, and heat pumps. Also, it makes possible an economizer mode for variable refrigerant flow units. With this invention, the units can distribute heating from a fuel-heat source without compressor operation. During refrigerant side economizer mode, the refrigerant pump in the units maintains circulation without compressor operation, with a fraction of energy consumption. To allow for longer distance between split-system units, the refrigerant pump if needed can operate during compressor operation.

DESCRIPTION OF DRAWING

FIG. 1. illustrates a heat pump schematic. Outdoor direct expansion coil 1 is connected by the hot gas piping through direction-selecting valve 6 to compressor 3. Indoor evaporator coil 2 is connected by liquid piping to refrigerant pump 7 through its direction-selecting valves. The direction-selecting valves can direct the hot gas from the compressor to the outdoor coil at cooling mode and to the indoor unit at heating mode. When the compressor is operating, the flow-directing valves of the pump direct the flow in the liquid piping to bypass the pump.

Expansion valve 4 serves the coil, or check valve 2 bypasses the expansion valve of the other coil, depending on whether cooling or heating mode is selected. When outdoor temperature allows, at economizer operation the pump maintains the refrigerant circulation, and the compressor is off and bypassed from the suction gas piping by its directing valves. When the pump is operating, the liquid flow is directed through the pump by its directing valves. In economizer cooling mode the pump discharge is directed by its directing-valves to the indoor coil. In fuel-heat based heating mode, the pump discharge is directed toward the outdoor coil. As described, the pump in either case delivers the liquid refrigerant from the lower refrigerant pressure coil to the higher refrigerant pressure and temperature coil, where the refrigerant evaporates.

BACKGROUND OF THE INVENTION Refrigerant Side Economizer

In many cases, providing a Refrigerant Side Economizer can eliminate the difficulty associated with the installation of an air-side or a water-side economizer

It is a code violation when neither an air-side nor a water-side economizer in large air conditioning and refrigeration systems is provided, as is the situation with many large variable refrigerant flow systems. The installation of a Refrigerant Side Economizer eliminates this worry.

Installing the Refrigerant Side Economizer in a walk-in cooler system will allow for significant energy saving since a walk-in cooler can be served by its remote condensing unit without compressor operation in the cold of winter.

SUMMARY OF THE INVENTION

Installation of the Refrigerant Side Economizer provides significant energy savings.

In the air conditioning unit, in the heat pump unit, or in the chiller, the refrigerant circulation can be maintained with a refrigerant pump instead of a compressor when the refrigerant in the condensing coil has a lower pressure than the refrigerant in the evaporator coil. This is the case when the outdoor temperature is cold, or when the evaporator coil is heated.

Serial operation of the refrigerant pump and compressor can also allow for an increase in the length of the refrigerant piping installation.

Energy consumption of the refrigerant pump accounts for only 1%-2% of the refrigerant compressor's energy use, which is proportional to the specific volume of the liquid-phase and of the vapor-phase of the refrigerant. Additionally, when circulation is maintained for only economizer operation, compressor use becomes unnecessary, and if used the compressor would elevate the pressure of the condensing coil even if condensation would be taking place in the lower pressure of the cold environment.

At this economizer mode, the refrigerant pump can deliver the liquid refrigerant against the elevated pressure of the evaporator coil with minimal energy consumption, without compressor operation, and with maintaining required cooling.

A similar situation exists for heating, where fuel-heated evaporator coil heat is distributed by the refrigerant piping network and by the indoor fan coil units. At this kind of heating, the expensive electric consumption of heat pump operation of the compressor can be replaced with less expensive fuel heat.

If the air conditioning or heat pump units are furnished with a refrigerant pump as a Refrigerant Side Economizer, there is no longer any need for an air-side economizer or a water-side economizer coil.

At the chiller, the economizer heat exchanger can be eliminated. The chiller unit can operate in economizer mode by itself.

In single or multi-zone split systems, self-contained units can provide economizer operation.

The remote condensing unit can run in economizer mode, serving walk-in coolers in the cold of winter without compressor energy use. 

1. In an air conditioner, cooler, chiller, or heat pump refrigerant circuit, installed with the pump described below, the condenser is connected on the liquid piping circuit's loop where the suction line of refrigerant bypasses the compressor, so that the pump can maintain circulation without compressor operation, or if used with compressor operation, it will boost refrigerant flow at parallel operation.
 2. The unit or system in claim 1 can be installed in such a way that the pump suction and discharge connections can be directed to either the evaporator or the condenser. In systems where there are refrigerant coils or refrigerant heat exchangers, separate pumps can be installed.
 3. In the units or systems of claim 1 or 2 the receiver or pneumatic storage tank can be installed in the liquid piping circuit between the pump and the condenser. 